Spread Of Foot-and-mouth Disease Virus Research Articles

A traditional evolutionary history of foot-and-mouth disease viruses in Southeast Asia challenged by analyses of non-structural protein coding sequences

Recombination of rapidly evolving RNA-viruses provides an important mechanism for diversification, spread, and emergence of new variants with enhanced fitness. Foot-and-mouth disease virus (FMDV) causes an important transboundary disease of livestock that is endemic to most countries in Asia and Africa. Maintenance and spread of FMDV are driven by periods of dominance of specific viral lineages. Current understanding of the molecular epidemiology of FMDV lineages is generally based on the phylogenetic relationship of the capsid-encoding genes, with less attention to the process of recombination and evolution of non-structural proteins. In this study, the putative recombination breakpoints of FMDVs endemic to Southeast Asia were determined using full-open reading frame sequences. Subsequently, the lineages’ divergence times of recombination-free genome regions were estimated. These analyses revealed a close relationship between two of the earliest endemic viral lineages that appear unrelated when only considering the phylogeny of their capsid proteins. Contrastingly, one lineage, named O/CATHAY, known for having a particular host predilection (pigs) has evolved independently. Additionally, intra-lineage recombination occurred at different breakpoints compared to the inter-lineage process. These results provide new insights about FMDV recombination patterns and the evolutionary interdependence of FMDV serotypes and lineages.

Seroprevalence of Foot-and-Mouth Disease in Susceptible Wildlife in Israel.

Foot-and-mouth disease (FMD) epidemics recur in Israel almost every year. Wild even-toed ungulates are seldom affected during these epidemics. The seroprevalence of FMD in wild ungulates during 2000 and 2005–2013 was estimated using anti-non-structural proteins ELISA. Overall, 209 samples were tested, comprising sera of 120 wild boar (Sus scrofa lybicus), 64 mountain gazelles (Gazella gazella gazella), 6 water buffaloes (Bubalus bubalis), and 19 Persian fallow deer (Dama dama mesopotamica). None of the tested animals presented clinical signs of FMD during blood collection. Sixteen samples [7.7% (95% confidence interval (CI95%) = 4.4–12.1%)] were found to be seropositive. Fifteen out of 120 samples (12.5%) from wild boar were seropositive, compared with only 1 out of 89 samples (1.1%) from all other species combined (Fisher’s exact test: p = 0.003). Most of the positive samples obtained from wild boar [13/15 (86.7%)] were collected during 2007, and analysis was restricted to that year and species only. The seroprevalence of FMD in this species during 2007 was estimated at 54.2% (CI95% = 32.8–74.5%; n = 24). A significant infection cluster, comprising nine seropositive samples collected in three different locations, was identified in the north-eastern part of Israel. These findings indicate that wild boar was affected during the 2007 FMD epidemic, even though wild boar presenting FMD typical clinical signs were not observed during that year. The actual role of wild boar in the spread of FMD virus in this epidemic, however, could not be determined. The negligible seroprevalence of FMD found for all other surveillance years indicates that ongoing circulation of FMD among wildlife in Israel is unlikely. It is concluded that while the role of wildlife species in the dynamics of FMD in Israel is usually limited, there might be occasions, in which wildlife plays a part in the spread of the virus.

Phylogeographic analysis of the 2000–2002 foot-and-mouth disease epidemic in Argentina

Foot-and-mouth disease (FMD) is a highly transmissible disease of hooved livestock. Although FMD has been eradicated from many countries, economic and social consequences of FMD reintroductions are devastating. After achieving disease eradication, Argentina was affected by a major epidemic in 2000–2002, and within few months, FMD virus spread throughout most of the country and affected >2500 herds. Available records and viral strains allowed us to assess the origins, spread and progression of this FMD epidemic, which remained uncertain. We used whole genome viral sequences and a continuous phylogeographic diffusion approach, which revealed that the viruses that caused the outbreaks spread fast in different directions from a central area in Argentina. The analysis also suggests that the virus that caused the outbreaks in the year 2000 was different from those found during the 2001 epidemic. To estimate if the approximate overall genetic diversity of the virus was related to disease transmission, we reconstructed the viral demographic variation in time using Bayesian Skygrid approach and compared it with the epidemic curve and the within-herd transmission rate and showed that the genetic temporal diversity of the virus was associated with the increasing number of outbreaks in the exponential phase of the epidemic. Results here provide new evidence of how the disease entered and spread throughout the country. We further demonstrate that genetic data collected during a FMD epidemic can be informative indicators of the progression of an ongoing epidemic.

Expression of porcine Mx1 with FMDV IRES enhances the antiviral activity against foot-and-mouth disease virus in PK-15 cells.

Foot-and-mouth disease virus (FMDV) is the most contagious pathogen in cloven-hoofed (two-toed) animals. Due to the rapid replication and spread of FMDV, novel therapeutic strategies are greatly needed to reduce or block FMDV shedding in cases of disease outbreak. Here, we generated an IRES-Mx1 construct in which the internal ribosome entry site (IRES) of FMDV was inserted between the promoter and open reading frame (ORF) of porcine myxovirus resistance protein 1 (poMx1). This construct provides more powerful protection against FMDV infection than the IRES-IFN construct that was previously generated by our group. The results indicate that this IRES-Mx1 construct was able to express poMx1 12 h after transfection and induce a robust immune response. In contrast to the control, the proliferation of virus in transfected cells was significantly inhibited, as evaluated by morphology monitoring, real-time RT-PCR, virus titration and Western blot. In addition, we also found that the antiviral activity in cells transfected with pc-IRES-Mx1 was abolished when the JAK/STAT pathway was repressed, which indicates that the antiviral mechanism of poMx1 is JAK/STAT pathway dependent. Taken together, our data suggest that the antiviral activity of poMx1 is possibly produced by affecting the host cells themselves, instead of interacting with the virus directly. The new construct reported here could be used as a novel effective therapy against FMDV infection.

Review of Air Dispersion Modelling Approaches to Assess the Risk of Wind-Borne Spread of Foot-and-Mouth Disease Virus

Foot-and-mouth disease virus (FMDV) is one of the most economically serious veterinary pathogens due to its negative effects on livestock and its highly infectious nature via a variety of transmission paths through oral and inhalation routes. Measures to enhance outbreak management can be designed according to analytical results predicted by mathematical models for wind-borne dispersion, an important path of virus transmission. Accurate atmospheric dispersion models are useful tools for properly determining risk management plans, while inaccurate models may conversely lead to accidental loss in two possible ways. Overly strict measures, e.g., slaughter for too wide an area, can cause severe economic difficulties, including irreversible loss of business operations for a number of farms. On the contrary, inestimable loss potentially caused by lax controls is a persistent threat. In this paper, available modelling procedures for forecasting the spread of FMDV, which have been used since the 1970s, each having its advantages and limitations, are reviewed for the purpose of ensuring suitable application in various conditions of any future emergency cases.

Modelling spread of foot-and-mouth disease in wild white-tailed deer and feral pig populations using a geographic-automata model and animal distributions

We investigated how the size and distribution of wild deer and feral pigs – species that might act as potential foot-and-mouth disease (FMD) virus maintenance hosts – might affect the persistence and spread of FMD. We used a susceptible-latent-infected-recovered geographic-automata model and spatially referenced data from southern Texas, USA. Within this study area, 100 locations were randomly selected and FMD virus spread was simulated (50 simulations each) at each location. As expected, the predicted sizes (km2) of the wild deer outbreaks were highly correlated (rSP>0.95) with the number of deer at incursion locations, the total number of deer within 2km of incursion locations, and the minimum and maximum deer herd size within 2km of incursion locations. However, the predicted sizes of the feral pig outbreaks were only moderately correlated (rSP 0.63–0.67) with the total, maximum and variance of the number of feral pigs within 2km of incursion locations. Lack of continuity within the feral pig herd distribution across the landscape makes predicting disease spread more difficult than for deer, a more homogenously distributed species. When assessing the potential of wild and feral animal species at a locality to act as maintenance hosts of FMD virus, estimates of the population size and distribution might serve as a useful indicator of potential outbreaks in some circumstances.

Abstract

A computer model of the spread of foot-and-mouth disease virus Sorensen, J. H., Mackay, D. K. J., Jensen, C. O. & Donaldson, A. I. (2000) An integrated model to predict...